An inflator for an inflatable vehicle occupant protection device, such as an air bag, may contain pressurized inflation fluid and ignitable material which, when ignited, heats the inflation fluid. Such an inflator may include an igniter containing a small charge of pyrotechnic material. The igniter further contains a bridgewire which is supported in an ignitable heat transferring relationship with the pyrotechnic material. When the air bag is to be inflated, an actuating level of electric current is directed through the bridgewire in the igniter. This causes the bridgewire to become resistively heated sufficiently to ignite the pyrotechnic material. The pyrotechnic material then produces combustion products which, in turn, ignite the ignitable material in the inflator.
The fluid pressure inside the inflator is increased by the heat generated upon combustion of the ignitable material. The inflation fluid then flows outward from the inflator and into the air bag to inflate the air bag more quickly than if the inflation fluid had not been heated and further pressurized.